Pushbutton keyboard system

ABSTRACT

A keyboard system in which a plurality of spaced sets of conductive members including U and rivet shaped are arranged at a surface of a support in electrical communication with conductive paths on an opposite surface of the support. A plurality of actuatable conductive elements, one for each set of conductive members, are provided to establish bridging electrical connection between conductive members of a set upon application of a preselected deflecting force to the conductive elements.

United States Patent 91 Boulanger [54] PUSHBUTTON KEYBOARD SYSTEM [75]Henry J. Boulanger, Cumberland,

Assignee: Texas Instruments Dallas,Tex.

Filed: June 1, 1971 Appl. No.: 148,503

Inventor:

[7 3} Incorporated,

[451 Apr. 3, 1973 Krakinowski .200/1 R Redman ..200/l R PrimaryExaminerDonald J. Yusko Assistant Examiner-Robert J. MooneyAttorney-Harold Levine, Edward J. Connors, Jr., John A. Haug, James P.McAndrews and Gerald B. Epstein [57] ABSTRACT [5-6] References Citedbets, are provided to establishbridgmg electrlcal connection betweenconductive members of a set upon UNITED STATES PATENTS application of apreselected deflecting force to the conductive elements. 3,600,5288/1971 Leposavic ..200/5 3,627,927 12/1971 7 Schmitz ..178/l7 C 17Claims, 7 Drawing Figures 44 t I m 48 9 I8 I I /4 4 42 PATH-HEDAPM 197a37257907,

SHEET 1 [IF 5 .5? Henry iBoulcmger- PATENTEUAPM 1973 SHEET l UF 5 5)flemy J. Boa/anger l/VVE/VTOR BY Heng/ Boa/anger PUSHBUTTON KEYBOARDSYSTEM The present invention relates generally to keyboard systems andmore particularly is directed to an improved pushbutton keyboard systemfor establishing electrical connections in response to actuation.

In recent years numerous types of keyboard systems have been developedfor use in transmitting coded electrical information for incorporationin various types of business machines such as electronic calculators.Typically such keyboard systems utilize pushbutton members appropriatelysymbolized in a manner indicative of a numeric or mathematical functiongenerated in response to depression of the pushbutton member toestablish electrical connections between various conductive paths and/orvarious circuit elements coupled to the system in order to achieve adesired function. However, particularly as the cost of associatedequipment has decreased dramatically in recent years coupled with anincrease in the use and availability of various devices incorporatingsuch systems the need has arisen for extremely inexpensive readilymanufacturable keyboard systems which may be economically and accuratelyproduced on a mass production basis with a high degree of accuraterepeatability. For example, the need for miniaturized electroniccalculators, units for addressing computer systems, credit cardverifiers, etc., which necessarily require various types of keyboardarrangements has enormously increased in recent years requiring theprovision of inexpensive and extremely durable keyboard systems whichmay be manufactured in a simple and economical manner on a relativelylarge volume basis-Particularly, in the computer field the need fordurable, inexpensive keyboard systems which can accurately addresselectrical information either directly to a system or through a remoteterminal or the like, while occupying a minimal amount of space, hasbecome increasingly urgent.

Accordingly, it is an object of the present invention to provide animproved keyboard system adapted for selectively establishing electricalinterconnections in response to mechanical actuation.

It is another object of the present invention to provide an improvedpushbutton keyboard system in which actuation of individual pushbuttonmembers establishes positive electrical interconnections fortransmitting electrical information.

It is a further object of the present invention to provide an improvedminiaturized pushbutton keyboard system which is relatively rugged anddurable and which is extremely economical to fabricate on a massproduction basis, and which is adapted for incorporation in variousdevices, such as electronic calculators, computer systems, etc.

Various additional objects and advantages of the present invention willbecome readily apparent from the following detailed description andaccompanying drawings wherein:

FIG. 1 is an exploded perspective view illustrating a preferredembodiment of a keyboard system in accordance with the presentinvention;

FIG. 2 is a vertical sectional view through the keyboard systemillustrated in FIG. 1;

' FIG. 3 is a partial plan view of the underside of the systemillustrated in FIG. 2;

FIG. 4 is an exploded perspective view of an alternative embodiment of akeyboard system similar to that illustrated in FIG. 1;

FIG. 5 is a vertical sectional view through the keyboard systemillustrated in FIG. 4;

FIG. 6 is a plan view of the underside of the system illustrated in FIG.5; and

FIG. 7 is a perspective view illustrating a typical variety ofelectronic calculator incorporating a keyboard system such as thatillustrated in the preceding embodiments.

Referring generally to the drawings, wherein corresponding elements inthe various views are indicated by common reference numerals, and inparticular initially to FIGS. 1-3, a keyboard system 10 in accordancewith the present invention is illustrated. The system generally includesa non-conductive or insulating support member 12 having a generallyplanar first surface 14 on which a plurality of conductive paths 16 aredisposed and arranged in a preselected pattern for transmittingelectrical information in response to selective interconnection ofportions thereof. At a second opposite surface 18 of the insulatingsupport member 12 a plurality of sets 20 of conductive support membersare provided which are arranged in a preselected configuration inelectrical communication with first preselected portions of theconductive paths 16. Associated with each of the conductive supportmembers are conductive contact members 22 similarly arranged at thesecond surface 18 of the insulating supporting layer in electricallyisolated relationship with the conductive support members and inelectrical communication with second preselected portions 16b of theconductive paths 16. A plurality of selectively actuatable conductiveelements 24 are also arranged adjacent the second surface 18 of theinsulating support layer and are respectively supported by andmaintained in continuous electrical contact with each of the sets 20 ofconductive support members and in selective disengagement with theassociated conductive contact members 22. The conductive elements 24 areadapted to be deflected into a position of engagement with theconductive contact members 22 in response to the application of apreselected deflecting force thereto so as to establish a bridgingelectrical contact between one of the sets 20 of conductive supportmembers and its associated conductive contact member 22, therebyelectrically connecting the first and second preselected portions 16a,16b of the conductive paths l6. Actuation of the conductive elements 24so as to effect the establishment of the aforementioned bridgingelectrical connection may be effected in various ways, but in theillustrated embodiment it is accomplished by the provision of aplurality of manually actuatable pushbutton members 26 which are carriedin a suitable casing 28 supported adjacent the second surface 18 of theinsulating support member 12 whereby the application of a preselecteddeflecting force to the conductive elements 24 is effected by actuationof a selected pushbutton member 26 by the application of a mechanicalforce thereto such as through the fingertips of an operator. As a resultof manual actuation of a selected pushbutton member 26 the preselecteddeflecting force is applied to the conductive element to effectdeflection thereof into a position of engagement with the conductivecontact member 22, thereby establishing the bridging electricalconnection between the set of conductive support members 20 and theconductive contact member 22 and hence establishing an electricalconnection between the first and second preselected portions 16a, 16brespectively of the conductive paths 16. In addition, if desired, asuitable device such as an integrated circuit shown in phantom andindicated generally by the reference numeral 30 may be carried by theinsulating support member 12 and suitably connected to selected portionsof the conductive paths 16 so as to process the signals established bythe interconnection of various portions of the conductive paths inresponse to the establishment of the bridging electrical connections.Similarly, if desired, a power supply (not shown) may be also carried onthe support member 12 to provide a selfcontained composite unit, or anexternal source of power may be utilized as the sole source of power oras an additional or alternative energy source.

More particularly, the insulating support member 12 is fabricated of arelatively rigid, non-conductive material which is adapted to providesupport for the keyboard system, as well as associated electroniccircuitry, power supplies, display means, etc., when the unit is to beincorporated in an electronic calculator system, a computer inputsystem, etc. In this regard the member 12 may be fabricated of asuitable, relatively rigid, insulation material such as epoxy bondedglass cloth generally sold under the trade description G- by the FormicaCompany. The material may have a thickness of approximately 1 16th inchwhich has been generally found sufficient to provide adequate mechanicalstrength for a miniaturized device of this nature. As previouslymentioned, the conductive paths 16 including the first and secondpreselected portions thereof 16a, 1612 respectively are arranged in adesired pattern at the first surface 14 (the underside of the supportmember 12, as illustrated in FIG. 2) in order to permit the transmissionof electrical information in response to selective interconnection ofvarious portions of the conductive paths upon the establishment of thebridging electrical connections. The pattern of conductive paths may bedeposited on the surface 14 of the support layer utilizing conventionalprinted circuit art techniques, such as masking, etching, engraving etc.In addition, a plurality of apertures 32 are provided extending throughthe thickness of the support member 12 between the first surface 14 andthe second surface 18 thereof so as to permit the selectiveestablishment of electrical communication between the conductive pathsat the surface 14 and the conductive support members 20 and contactmembers 22 arranged at the opposite surface 18. In this regard theapertures may be provided prior to or subsequent to the deposition ofthe conductive paths, thereby providing a pre-punched support boardprepared for further fabrication operations.

In the illustrated embodiment the sets of conductive support members 20are arranged to define a plurality of spaced 'sets of pairs of generallyU-shaped, conductive members preferably comprising staples arranged atthe surface 18 of the support layer 12. Such an arrangement has beenfound to be extremely advantageous in achieving enhanced case offabrication of the system since the staples may be readily insertedthrough the apertures 32 in the pre-punched support member 12 utilizingsuitable high-speed automated stapling equipment. Similarly, electricalcommunication may be conveniently established between these staples andselected portions of the conductive paths 16. As shown, the staples 20each include a main body portion 34 of a generally looped configurationterminating in a pair of legs 36 which are received within the apertures32 in the support layer 12. The apertures 32 are of a size sufficient toaccommodate the legs 36 in a close-fitting relationship, while the outerends of the legs are crimped against the surface 14 and are in contactwith the selected portions of the conductive paths 16, such as the firstpreselected portions 16a. Consequently, a rigid mechanical connection isestablished and the electrical contact may be improved by soldering thecrimped portions of the legs into position. In addition, as shown, themain body portion 34 of each of the staples comprising the plurality ofsets of support members projects a first preselected distance outwardlyfrom the surface 18 of the support member 12 so as to define conductivesupport areas spaced from the surface 18 for carrying the conductiveelements 24. Similarly, the associated conductive contact members 22 arealso illustrated as generally U-shaped conductive members, preferablycomprising staples each having a main body portion 38 which terminatesin a pair of legs 40 which project through apertures 42 extendingthrough the thickness of the support member 12 similarly to theappertures 32, but providing communication with other portions of theconductive paths 16, such as the second preselected portions 16b. Thelegs 40 extend through the apertures 42 with the outer ends thereofbeing crimped against the surface 14 of the support layer 12 preferablyin contact with other portions of the conductive paths 16, such as thesecond preselected portions 16b. The apertures 42 are of a sizesufficient to accommodate the legs 40 of the staple 22 while the outerends of the legs 40 are crimped against the surface 14 in contact withthe second preselected portions 16b of the conductive paths to rigidlysecure the staple to the member 12. In addition, the outer ends of thelegs 40 crimped in position against the second preselected portions 16bof the conductive paths 16 may be soldered in this position to providean improved electrical contact as shown. One of the contact staples 22is arranged intermediate each of the pairs of support staples 20 and maybe of slightly smaller gauge such that its main body portion 38 projectsoutwardly from the surface 18 a second preselected distance differentthan the first preselected distance which the body portion 34 of thesupport stapl'es 20 projects from the surfaces so as to facilitatemaintenance of selective disengagement between the conductive elements24 and the contact staples 22, as will be subsequently explained. Theconductive support staples 20 and the conductive contact staples may befabricated of various materials and material combinations depending uponthe properties desired. For example, in one preferred embodiment thestaples are fabricated of gold-plated nickel wire in order to provide arelatively non-reactive material having good surface contact properties.As other examples, the staples may be fabricated of goldplated stainlesswith a flash of nickel intermediate the central portion is subjected toa preselected deflecting force while automatically returning to itsoriginal position upon removal of the force, whereby the element isprovided with a memory function. Of course, segments of other hollowbodies having double curved surfaces may be utilized in providing theconductive elements. The element 24 may be arranged such that itundergoes a snap-action deflection into its overcenter position in orderto establish the aforementioned bridging electrical contact. In thisregard referring particularly to FIG. 2, one of the elements indicatedby the numeral 24a is shown in its overcenter position in response toactua- 7 tion by a depressed pushbutton member indicated by referencenumeral 26a. However, it should be noted that in certain instances thecentral portion of conductive element 24 may be sufficiently closelyspaced to the contact staple 22 that the element 24 need not becompletely deflected into its overcenter position in order to contactthe staple 22 for establishing the requisite bridging contact. Thus,upon application of the preselected deflecting force to the centralportion of the conductive element 24 in response to actuation ordepression of the pushbutton member 26 the element 24 is caused toundergo a snap-action deflection into its overcenter position. Inaddition, as a result of this snap-action deflection a tactile feed-backis provided which may be sensed in the finger tips of the operatoractuating a particular pushbutton. Furthermore, an audibleacknowledgment of deflection may accompany the snap-action deflectionwhich may be further sensed by the operator as an additional indicationof actuation of a pushbutton member to transmit a desired electricalsignal. The conductive elements 24 preferably comprise gold-platedstainless steel discs and in one preferred embodiment may be fabricatedof A.I.S.I. (American Iron and Steel Institute) Type 302 StainlessSteel, which comprises by weight approximately 0.15 percent carbon, 2.00percent (max.) manganese, 1.00 percent (max.) silicon, 17 percent to 19percent chromium, 8 percent to percent nickel and the balance iron, witha thin gold plating over its exposed contact surfaces.

Each of the conductive elements 24 is maintained in axial registry withthe conductive contact staple 22 as sociated with each of the sets ofsupport staples with the central portion thereof spaced from the contactstaple 22. The marginal edges of the conductive elements 24 aresupported on the main body portions 34 of the support staples 20 of eachset such that the conductive element 24 is in continuous electricalcontacttherewith and hence with the first preselected portions 16a ofthe conductive paths 16. Similarly, the central portion of theconductive elements 24 which are in registry with the main body portions38 of the contact staples 22 remain in selective disengagement with thecontact staples until deflected by actuation of a pushbutton member 26,whereupon the bridging electrical connection is established between aset of conductive support staples 20 and its associated conductivecontact staple 22 and hence between the first and second preselectedportions 16a, 16b of the conductive path 16.

In order to further support each of the conductive elements 24 andprovide lateral restraint therefor a carrier sheet of insulatingmaterial 44 is disposed adjacent the surface l3 of the support member 12overlying the plurality of sets of conductive support staples 20 andassociated conductive contact staples 22. The sheet 44 includes aplurality of apertures 46 which are of a size sufficient to accommodatethe conductive elements 24 therein and arranged in registry with theplurality of sets of conductive support staples 20 and the associatedconductive contact staples 22. More particularly, the conductiveelements 24 are disposed within the apertures 46, which are of a sizeslightly larger than the spacing intermediate the staples comprisingeach of the sets of conductive support staples. Accordingly the sheet 44maybe maintained essentially in abutment with the surface 18 of thesupport member 12 with the main body portions 34 of the conductivesupport staples 20 which support the elements 24 extending slightly intothe apertures 46. The conductive elements 24 are arranged within theapertures 46 and have opposed marginal portions resting on the main bodyportions 34 of the conductive support staples 20. Thus, support, as wellas lateral restraint for the conductive elements 24 is provided. Inaddition, as may be noted, particularly in FIG. ll, each of theapertures 46 is of a preselected shape including a pair of opposedparallel walls 46a which are of a generally straight-line configuration,these generally straight-line wall portions being arranged to bound themain body portions 34 of the conductive support staples 20 which extendinto the apertures 46. The other pair of opposed wall portions 46b ofeach of the apertures 46 are arranged in a generally curvilinearconfiguration curving outwardly from the center of the apertures 46 soas to more efficiently accommodate the generally circular conductiveelements or discs 24. In this regard by virtue of providing theapertures 46 having a shape as illustrated certain advantages areachieved in that the overall space occupied by the apertures isminimized, since only one of the two dimensions of the apertures areincreased while the other dimension is minimized, thereby maximizing theamount of material which remains to define the layer 44 in'order toenhance its structural strength and rigidity. This is advantageous inview of the small size of the layer 44 and the large number of apertureswhich are employed. The sheet 44 may be fabricated of a suitablenonconductive material such as a suitable glass cloth reinforced epoxy.In addition, the marginal portions of the sheet 44 which extend beyondthe sets of support staples 20 at opposed sides of the support board 12preferably are bonded or sealed to the marginal portions of supportmember 12 so as to facilitate the formation of an environmentally sealedunit.

In certain instances, it has been found desirable to further restrainthe conductive elements 24 in their respective positions by providing arelatively thin, flexible sheet or film of an insulating forcetransmitting over-layer sheet or film 48, as shown, which is arrangedintermediate the sheet 44 and the casing 28 which supports thepushbutton members 26. The over-layer 48 may comprise a material, suchaspolyethylene terephthalate, commonly sold under the trade name Mylar,and may be suitably bonded or sealed to the exposed surface of the layer44 and hence functions to prevent the conductive elements 24from-inadvertently being removed or falling fromvtheir desired positionswithin the apertures 46, as well'as completing an environmental seal forthe unit.

The pushbutton members 26 are each appropriately symbolized at theirouter exposed surfaces in a manner indicative of the electronic functionassociated with actuation of a selected pushbutton member whichestablishes the requisite bridging electrical connection between theconductive support staples 20 and the conductive contact staple 22 andhence between the first and second preselected portions 16a, 16b of theconductive paths 16. In addition, each of the pushbutton similarlyfabricated of a suitable rigid, non-conductive plastic material, or thelike. In this regard each of the pushbutton members 26'include a flangedportion 52 which integrally extends from one pair of opposed lower edgesurfaces thereof. These flange portions 52 are, adapted to be receivedwithin accommodating channels or slots 54 inthe casing 28 when themembers 26 are positioned in the casing 28 to preclude lateral motion ofthe pushbutton elements 26 within the casing, while, permitting movementof the pushbutton members normal to the planar surface of the casing 28upon actuation thereof. In addition, the casing 28 includes a pair ofdepending flange members 56 the spacing therebetween' being of'a sizesufficient to accommodate the marginal edge portions 12a, 12b of thesupport member 12 if it is desired to provide an environmental sealbetween these marginal edge portions 12a, 12b and the inner surfaces ofthe flange members 56, when the casing 28 positioned in abutment withthe overlayer sheet 48 with the pushbutton members aligned with therespective'conductive elements 24. Thus, in operation the pushbuttonmembers are precluded from lateral movement within the casing butsupport staples 20 associated therewith.

Referring now to FIGS. 4-6 an alternate embodiment of a keyboard systemsimilar to that illustrated in FIGS. 1-3 is shown in which a modifiedarrangement for carrying the conductive elements is provided. Moreparticularly, in this embodiment a support member. of insulatingmaterial similar to the support member 12 is provided having apreselected pattern of conductive paths 62 arranged at a first surface64vthereof while a plurality of sets of conductive supportmembers 66 arearranged at a second opposed surface 68of the board with an associatedconductive contact member 70 being provided associated with each of thesets of con- .body ofth emembers 26. The casing 28 may be ductivesupport members spaced from and electrically isolated from the set ofsupport members. The conductive support members 66 are adapted to bedisposed in cooperating apertures 72 which are provided extendingthrough the thickness of the support board between the first and secondsurfaces 64, 68 so as to permit electrical communication to beestablished between each set of conductive support members 66 and firstpreselected portions 62a of the conductive paths 62,

when these conductive support membersare inserted the sets of conductivesupport members 66 is adapted to define a generally planar support areafor supportingly receiving a conductive element 76 similar to theconductive element-24. The conductive element 76 is supported incontinuous electrical contact with the set of support member 66 andhence in contact with the first preselected portions 62a of theconductive paths 62. In addition, the conductive element 76 remains in,selective disengagement with the associated conductive contact memberand accordingly, each set of support members remains electricallyisolated from its associated contact member 70 until deflection of theconductive element 76 is effected. Such deflection is accomplished in amannersimilar to that described'in connection with the precedingembodiment in response to theapplication of a preselected deflectingforce to the conductive element 76 to establish engagement between theconductive element 76 and the conductive contact member 70, therebyestablishing a bridging electrical contact between the set of conductivesupport members 66 and the conductive contact member 70 and hencebetween the first and preselected portions 62a, 62b of the conductivepaths 62. The application of the preselected deflecting force to theconductive element 76 is again accomplished by the provision of aplurality of pushbutton members 78 maintained in registry with therespective conductive elements 76 such that actuation or depression of apushbutton member 78 is effective to cause deflection of a conductiveelement in order to cause it to engage its associated conductive contactmember thereby establishing the requisite bridging electrical contact.The pushbutton members 78 are similarly carried within a suitablesupport casing 80 which includes a plurality of slots 82 for receivingthe body of the pushbutton members 78 therein, the pushbutton membersbeing movable from a retracted to an actuating position in response tothe application of a mechanical force to the exposed surfaces thereof,such as by manual actuation As previously mentioned, in accordance withan important advantage of the present invention a keyboard system isprovided which is particularly suitable for fabrication by rapid,accurate, and inexpensive mass production techniques. The embodimentillustrated in FIGS. 4-6 similarly provides such advantages in that thesupport board 60 may be similarly provided in a prepunched configurationincluding the apertures 72, 74 for accommodating the conductive supportmembers and the conductive contact members, while a desired pattern ofconductive paths may be deposited on the surface 64 thereof utilizingconventional printed circuit art techniques to permit the selectedelectrical connections to be made between respective portions of theconductive paths. However, rather than employing staples, as in thepreceding embodiment each of the sets of conductive support members 66preferably comprises a plurality of collared rivets each of whichincludes a shank 82 and a flanged collar 84 with the shank adapted to beinserted in the aperture 72 while the collar 84 rests against thesurface 68 of the support board, a portion of the shank projectingoutwardly therefrom and the opposite end 86 of the shank is crimpedagainst the surface 64 of the support member 60 in electrical contactwith the first preselected portions 62a of the conductive path 62,thereby mechanically restraining the rivet in position with respect tothe support member and the conductive path 62. In addition, the crimpedend 86may be soldered in position to assure a good electrical contactwith the first preselected conductive path 62a. In the illustratedembodiment each set 66 includes four of the previously described rivetsarranged to define a generally enclosed area with the flanged collarportions 84 of each of the rivets defining a generally planar supportarea for the conductive element 76. It should be noted that a lesser orgreater number of rivets, of course, may be utilized; In addition, theassociated conductive contact member 70 is arranged generally centrallywithin the area defined by the four rivets 66 and preferably comprises aheaded rivet including a shank portion 88 which is disposed within theaperture 74 with one end 90 being crimped against the surface 64 of thesupport board 60 as shown while its opposite end terminates in a head 92of a larger diameter than the aperture 74 such that the rivet 70 ismechanically restrained with respect to the 1-3. The element 76 isarranged such that it similarly undergoes deflection movement into itsovercenter position in order to establish the aforementioned bridgingelectrical contact between the set of support rivets 66 and the contactrivet 70 and hence between the first and second preselected portions62a, 62b of a preselected deflecting force to the central portion of Vthe conductive element 76 in response to actuation or depression of theselected pushbutton member 78 the element 76 is caused to undergo asnap-action deflection into its overcenter position and engages the headsupport member 60, subsequent to the crimping of its end 90 against thesurface 64. The crimped end 90 is in electrical contact with the secondpreselected conductive path 62b and similarly may be soldered inposition to assure a good electrical contact therewith. In addition, asshown the head 92 of the rivet 70 may be displaced outwardly from thesurface 68 of the support member a lesser distance than the collar 84 ofthe support rivets 66 such that the central portion of the conductiveelement 76 may be maintained in selective disengagement therewith, aswill now be explained in detail.

More particularly, the conductive elements 76 are generally similar tothe elements 24, as described in connection with the embodimentillustrated in FIGS.

92 of the contact rivet thereby establishing an abrupt, instantaneousand positive bridging electrical contact between the support rivets 66and the contact rivet 70 and hence between the first. and secondpreselected portions 62a, 62b of the conductive paths 62. In addition,similarly to the preceding embodiment, as a result of this snap-actiondeflection a tactile feedback is provided which may be sensed in thefinger tips of the operator actuating a particular push-button, and anaudible acknowledgment of deflection may accompany the snap-actiondeflection and may be further sensed by the operator as an additionalindication of actuation of a pushbutton member to transmit a desiredelectrical signal.

In order to further aid in maintaining the elements 76 -in position aswell as to facilitate the formation of an environmental seal, it hasbeen found advantageous in certain instances to provide an overlayer 94of a flexible force transmitting material arranged intermediate thepushbutton members 78 and the conductive elements 76. In this regardlateral movement of the conductive elements 76 is precluded by virtue ofthe disposition of the elements 76 within the area defined by each ofthe sets of support rivets 66 resting on the flanged collar portions 84,with the marginal edges of the conductive elements 76 being laterallyrestrained by the portions of the shanks 82 which project outwardlybeyond the collars 84. However, in order to prevent the elements 76 frombeing inadvertently removed from or falling from the unit the overlayer94 may be provided, as shown, and may be suitably bonded to the marginaledge portions of the support board 60 to form an environmental seal. Theoverlayer 94 may be fabricated of a strong, flexible, thin insulationmaterial, such as polyethylene terephthalate, commonly sold under thetrade name Mylar.

As previously mentioned, the pushbutton elements 78 are suitably carriedwithin the slots 82 in the casing and as shown have outer exposedsurfaces which are appropriately symbolized in accordance with theelectrical information which is to be transmitted in response toactuation thereof. In addition, a generally centrally located protrudingmember 96 extends from response to actuation or depression of thepushbutton members 78. A pushbutton member 780 is illustrated in FIG. inits depressed -or actuated condition to show the establishment of thebridging electrical contact between the set of conductive support rivets66 and the conductive contact rivet 70, whereby the requisite bridgingelectrical contact is established between selected portions of theconductive paths 62. Each of the pushbutton members 78, similar to thepreceding embodiment, also may include a pair of opposed flanges 97which are adapted to be received in cooperating channels 98 in the wallof the slots 82 in the casing to provide improved lateral support forthe pushbutton members 76. The casing 80 also preferably includes a pairof depending flange portions 99 extending along its longitudinal edgesspaced apart a distance slightly greater than the lateral dimension ofthe support member 60 so that the inner portions of the flanges 99 maybe sealed to the marginal edges of the support member 60 if it isdesired to provide an environmentally sealed unit. The casing 80 as wellas the pushbutton members 78 may be fabricated of a suitable insulatingplastic material.

In operation it may be seen that similarly to the embodiment illustratedin FIGS.- 1-3 the actuation or depression of a selected pushbuttonmember 78 effects deflection of its associated conductive element 76 soas to effect the establishment of the bridging electrical contactbetween the support rivets 66 and the contact rivet 70 and hence betweenthe first and second preselected portion 62a, 62b of the conductivepaths 62 so as to permit the transmission of an appropriate electricalsignal. In addition, as illustrated in FIGS. 4 and 6, if desired,suitable semiconductor devices or the like illustrated in phantom as adual-in-line package integrated circuit 100 may be provided with itslead members 102 extending through suitable apertures 104 in the supportboard 60 and maintained in contact with requisite portions of theconductive paths 62 so as to selective couple the various circuitelements thereof (not shown) to the paths 62 in order to process theelectronic information being transmitted upon interconnection ofselected portions of the conductive paths. Similarly, if desired, asuitable power supply means (not shown) may be also mounted on thesupport member 60.

. Referring to the FIG. 7 embodiment a composite unit indicatedgenerally by the reference numeral 104 is illustrated, including aplurality of pushbutton members 106 supported within a causing 108 whichis mounted in overlying relationship with a support board 110 which mayinclude conductive support areas, conductive contact areas, conductiveelements, conductive paths etc., all as shown and described in thepreceding embodiments. In addition, the unit 104 includes a visualdisplay window 1 12 so as to provide a visual indication of operation ofthe unit when it is being utilized as an electronic calculator, forexample, as an input to a computer system, etc. Similarly, if desired,the unit 104 may include a suitable print out mechanism to provide apermanent record, if desired.

Thus, a unique keyboard system has been described in detail in which aparticularly advantageous bridging electrical contact system is providedthe system being 'particularly adapted for incorporation in varioussystems such as electronic calculators, computer systems, etc.

Various changes and modifications in the abovedescribed embodiments willbe readily apparent to those skilled in the art and any of such changesof modifications are deemed to be within the spirit and scope of thepresent invention as set forth in the appended claims.

I claim:

1. A selectively energizable keyboard system comprising an electricallyinsulating support member having a generally planar first surface onwhich a plurality of conductive paths are disposed arranged in apreselected pattern adapted to transmit electrical information inresponse to selective interconnection of por-' tions of said paths,

a plurality of spaced apart setsof conductive support members arrangedin a preselected configuration at a second opposite surface of saidsupport member in electrical communication with first preselectedportions of said paths,

conductive contact members associated with each of said plurality ofsets of conductive support members, said contact members being arrangedat said second surface of said support member each in electricallyisolated relationship with its associated conductive support member andin electrical communication with second preselected portions of saidpaths, and

a plurality of selectively actuatable conductive elements adjacent saidsecond surface, one of said elements being supported by and maintainedin continuous electrical contact with each of said sets of conductivesupport'members and in selective disengagement with said conductivecontact member, said conductive elements being adapted to be deflectedinto a position of engagement with said conductive contact member so asto establish an electrical connection between said first and said secondpreselected portions of said paths in response to the application of apreselected deflecting force to said conductive element.

2. A-system in accordance with claim 1 wherein means are provided forapplying the preselected deflecting force to said conductive elements,including a plurality of pushbutton members adapted. to. be manuallyactuated to apply the deflecting force to said conductive elements toeffect deflection thereof into a position of engagement with saidconductive contact member, each of said pushbutton members having aforce applying surface in registration with a conductive element andanother surface adapted to be symbolized in a manner indicative of theelectrical information transmitted in response to the establishment ofthe electrical connection between said first and said second preselectedportions of said paths.

3. A system in accordance with claim 1- wherein each of said sets ofconductive support members-include a plurality of spaced first metallicmembers arranged to define at least a partially enclosed area at saidsecond surface of said insulating support member, said first metallicmembers extending through said insulating support member and terminatingin electrical contact with said first preselected portions of saidconductive paths.

, support for said conductive element.

6. A system in accordance with claim 5 wherein said second metallicmembers project outwardly a second preselected distance less than saidfirst preselected distance from said second surface of said insulatingsupport member so as to remain spaced from said conductive element untilsaid conductive element is deflected into engagement therewith so as toestablish the bridging electrical connection between the set ofconductive support members and the associated conductive contact member.

7. A system in accordance with claim 6 wherein said conductive elementsare each of a generally circular configurationhaving marginal edgeportions supported on the generally planar support defined by said firstmetallic members and a generally central portion maintained in selectivedisengagement with and adapted to be deflected into engagement with saidconductive contact member, said conductive elements each having a convexsurface of curvature adapted to receive the preselected deflecting forcein registration with an associated conductive contact member, saidconvex surface being adapted to be deflected into a concaveconfiguration in engagement with said conductive contact member inresponse to the application of the preselected force.

8. A system in accordance with claim 7 wherein a relatively thinflexible insulating, force-transmitting overlayer is secured to saidinsulating support board in overlying relationship with respect to saidconductive elements so as to maintain said conductive elements in aposition supported by said first, metallic members.

9. A system in accordance with claim 6 wherein said first metallicmembers each comprise a generally U- shaped member including a pair oflegs extending through apertures in said insulating support member andbeing rigidly crimped into position at said first sur face of saidinsulating support member in electrical contact with said firstpreselected portions of said conductive paths and an integral bodymember joining said legs, said body being supported at said secondsurface of said insulating support member and projecting outwardlytherefrom said first preselected distance, and said second metallicmembers each comprise a generally U-shaped member including a pair oflegs extending'through apertures in said insulating support member andbeing rigidly crimped into position at said first surface of saidinsulating support member in electrical contact with said secondpreselected portions of said conductive paths and an integral bodymember joining said legs, said body being supported at said secondsurface of said insulating support member and projecting outwardlytherefrom said second preselected distance.

10. A system in accordance with claim 9 wherein said first metallicmembers comprise a pair of staples secured to said insulating supportmember, each of said sets of conductive support members includingsaidpair of staples separated by a preselected distance to define thegenerally planar support for said conductive elements, and said secondmetallic member comprises another staple secured to said insulatingsupport member intermediate said pair of staples.

11. A system in accordance with claim 10 wherein said conductiveelements are each of a generally circular configuration having opposedmarginal potions supported on said pair of staples and having agenerally central portion spaced from and maintained in selectivedisengagement with said another staple and adapted to be deflected intoengagement with said another staple in response to the application ofthe preselected deflecting force to said conductive element therebyestablishing a bridging electrical contact between said pair of staplesand said another staple so as to effect an electrical connection betweensaid first and second preselected portions of said conductive paths.

12. A system in accordance with claim 6 wherein said first metallicmembers each include a shank extending through an aperture in saidinsulating support member and having an annular collar at one end of agreater diameter than the aperture to preclude complete passage of saidshank through the aperture, said collar abutting said second surface ofsaid insulating support member and defining a portion of the planarsupport for one of said conductive elements, the opposite end of saidshank being crimped against said first surface of said insulatingsupport member to effect rigid emplacement of said first metallicmember, and said second metallic member each include a shank extendingthrough an aperture in said insulating support member and having a headat one end of a greater diameter than the aperture to preclude completepassage of the shank therethrough, said head abutting said secondsurface of said insulating support member, the opposite end of saidshank being cramped against said first surface of said insulatingsupport member to effect rigid emplacement of said second metallicmember.

13. A system in accordance with claim 12 wherein said first metallicmembers comprise collared rivets secured to said insulating supportmember, each of said sets of conductive support members including aplurality of collared rivets spaced to accommodate said conductiveelements in supporting relationship on said annular collars, and saidsecond metallic member comprises a headed rivet generally centrallylocated with respect to said set of collared rivets.

14. A system in accordance with claim 13 wherein said conductiveelements are each of a generally circular configuration having amarginal boundary supported on said annular collars of said collaredrivets and having a generally central portion spaced from and maintainedin selective disengagement with said headed rivet and adapted to bedeflected into engagement therewith in response to the application ofthe preselected deflecting force to said conductive element therebyestablishing a bridging electrical contact between said set of collaredrivets and said headed rivet so as to effect an electrical connectionbetween said first and second preselected portions of said conductivepaths.

15 A selectively energizable keyboard system comprising an electricallyinsulating support board having a first surface carrying a plurality ofconductive paths arranged in a preselected pattern and adapted totransmit electrical information in response to selective interconnectionof portions thereof,

a plurality of spaced sets of conductive staples arranged in apreselected configuration at a second opposite surface of said supportboard to define a plurality of generally planar support areas the endsof each of said staples extending through apertures in said supportboard and terminating in electrical contact with first preselectedportions of said conductive paths,

a plurality of associated conductive staples at said second surface, oneof said associated staples being arranged intermediate the staples ineach of said sets and electrically isolated therefrom, the ends of eachof said associated staples extending through apertures in said supportboard and terminating in electrical contact with second preselectedportions of said conductive paths,

a. plurality of selectively actuatable, generally circular, conductivediscs adapted to undergoflexing movement in response to the applicationof a preselected deflecting force thereto respectively disposed on saidplanar support areas with marginal portions thereof supported by andmaintained in substantially stationary electrical contact with said setsof conductive staples and the central portion thereof is selectivedisengagement with said associated conductive staples, the centralportions of said conductive discs being adapted to be deflected into aposition of engagement with said associated conductive staples so as toestablish a bridging electrical contact between a set of conductivestaples and its associated conductive staple, thereby electricallyconnecting said first and second preselected portions of said conductivepaths in response to the application of a preselected deflecting forceto said conductive element,

an overlayer of insulating material supported at said second surface ofsaid support board, said overlayer including a plurality of aperturesexposing said sets of conductive staples and said associated staples,said apertures being adapted to accommodate said conductive discs torestrain lateral 1 movement thereof while permitting deflection thereof,and means for applying the preselected deflecting force to saidconductive discs including a plurality of pushbutton members adapted tobe manually actuated to apply the preselected deflecting force to saidconductive discs to effect deflection of the central portion thereofinto a position of engagement with said associated conductive staple,each of said pushbutton members havinga force applying surface inregistration with a conductive disc and an exposed surface adapted to besymbolized in a manner indicative of the electrical informationtransmitted in response to the establishment of the electricalconnection between said first and second portions of said conductivepaths.

16. In an electronic calculator;

a pushbutton keyboard system adapted to enter electrical information inresponse to actuation, said keyboard system including an insulatingsupport board having a first surface on which a plurality of conductivepaths are arranged in a preselected pattern and adapted to transmitelectrical information in response to energization thereof, 1

a plurality of spaced sets of conductive support members arranged in apreselected configuration at a second opposite surface of saidinsulating support board to define a plurality of support areas spacedfrom said second surface and in electrical communication with firstpreselected portions of said conductive paths, 7

a plurality of conductive contact members associated with said pluralityof support members one of said contact members being arranged within thearea defined by each of said sets of contact members and in electricalcommunication with second preselected portions of said conductive paths,

a plurality of selectively actuatable, generally circular, conductivediscs respectively disposed on said support areas with marginal portionsthereof supported by and maintained in substantially stationaryelectrical contact with said support members the central portionsthereof being in selective disengagement with said associated contactmembers and being adapted to be deflected into a position of engagementwith said associated contact member in response to the applicationthereto of a preselected deflecting force so as to establish a bridgingelectrical connection between a set of conductive support members andits associated conductive contact member, thereby electricallyconnecting said first and said second preselected portions of saidconductive paths,

means disposed adjacent said second surface for restraining movement ofsaid conductive disc's other than flexing movement thereof, and

means for applying the preselected deflecting force to said conductiveelements including a plurality of pushbutton members adapted to beactuated to apply the preselected deflecting force to said conductivediscs to effect deflection of the: central portion thereof into aposition of engagement with the associated conductive contact member,each of said pushbutton members having a force applying surface adjacenta conductive disc and an exposed surface adapted to be symbolized in amanner indicative of the electrical information to be transmitted by theestablishment of the bridging electrical connection between said firstand second portions of said first and second conductive paths.

17. A selectively energizable keyboard system comprising an electricallyinsulating support member having a generally planar first surface onwhich a plurality of conductive paths are disposed arranged in apreselected pattern adapted to transmit electrical information inresponse to selective interconnection of pottions of said paths, I

a plurality of spaced apart generally U-shaped first conductive membersarranged in a preselected configuration at a second opposite surface ofsaid support member, the ends of each first member extending throughapertures in the support member and terminating in electricalcommunication with first preselected portions of said paths,

a plurality of generally U-shaped second conductive members, a secondmember associated with each of said first conductive members, saidsecond conductive members being arranged at said second surface of saidsupport member each in electrically isolated relationship with itsassociated first conductive member, the ends of each second memberextending through apertures in the support member and terminating inelectrical communication with second preselected portions of said paths,

a plurality of selectively actuatable conductive ele-

1. A selectively energizable keyboard system comprising an electricallyinsulating support member having a generally planar first surface onwhich a plurality of conductive paths are disposed arranged in apreselected pattern adapted to transmit electrical information inresponse to selective interconnection of portions of said paths, aplurality of spaced apart sets of conductive support members arranged ina preselected configuration at a second opposite surface of said supportmember in electrical communication with first preselected portions ofsaid paths, conductive contact members associated with each of saidplurality of sets of conductive support members, said contact membersbeing arranged at said second surface of said support member eaCh inelectrically isolated relationship with its associated conductivesupport member and in electrical communication with second preselectedportions of said paths, and a plurality of selectively actuatableconductive elements adjacent said second surface, one of said elementsbeing supported by and maintained in continuous electrical contact witheach of said sets of conductive support members and in selectivedisengagement with said conductive contact member, said conductiveelements being adapted to be deflected into a position of engagementwith said conductive contact member so as to establish an electricalconnection between said first and said second preselected portions ofsaid paths in response to the application of a preselected deflectingforce to said conductive element.
 2. A system in accordance with claim 1wherein means are provided for applying the preselected deflecting forceto said conductive elements, including a plurality of pushbutton membersadapted to be manually actuated to apply the deflecting force to saidconductive elements to effect deflection thereof into a position ofengagement with said conductive contact member, each of said pushbuttonmembers having a force applying surface in registration with aconductive element and another surface adapted to be symbolized in amanner indicative of the electrical information transmitted in responseto the establishment of the electrical connection between said first andsaid second preselected portions of said paths.
 3. A system inaccordance with claim 1 wherein each of said sets of conductive supportmembers include a plurality of spaced first metallic members arranged todefine at least a partially enclosed area at said second surface of saidinsulating support member, said first metallic members extending throughsaid insulating support member and terminating in electrical contactwith said first preselected portions of said conductive paths.
 4. Asystem in accordance with claim 3 wherein said conductive contactmembers each comprise a second metallic member arranged generallycentrally within said partially enclosed area at said second surface ofsaid insulating support member, said second metallic member extendingthrough said insulating support member and terminating in electricalcontact with said second preselected portions of said conductive paths.5. A system in accordance with claim 4 wherein said first metallicmembers project outwardly a first preselected distance from said secondsurface of said insulating support member to define a generally planarsupport for said conductive element.
 6. A system in accordance withclaim 5 wherein said second metallic members project outwardly a secondpreselected distance less than said first preselected distance from saidsecond surface of said insulating support member so as to remain spacedfrom said conductive element until said conductive element is deflectedinto engagement therewith so as to establish the bridging electricalconnection between the set of conductive support members and theassociated conductive contact member.
 7. A system in accordance withclaim 6 wherein said conductive elements are each of a generallycircular configuration having marginal edge portions supported on thegenerally planar support defined by said first metallic members and agenerally central portion maintained in selective disengagement with andadapted to be deflected into engagement with said conductive contactmember, said conductive elements each having a convex surface ofcurvature adapted to receive the preselected deflecting force inregistration with an associated conductive contact member, said convexsurface being adapted to be deflected into a concave configuration inengagement with said conductive contact member in response to theapplication of the preselected force.
 8. A system in accordance withclaim 7 wherein a relatively thin flexible insulating,force-transmitting overlayer is secured to said insulating support boarDin overlying relationship with respect to said conductive elements so asto maintain said conductive elements in a position supported by saidfirst metallic members.
 9. A system in accordance with claim 6 whereinsaid first metallic members each comprise a generally U-shaped memberincluding a pair of legs extending through apertures in said insulatingsupport member and being rigidly crimped into position at said firstsurface of said insulating support member in electrical contact withsaid first preselected portions of said conductive paths and an integralbody member joining said legs, said body being supported at said secondsurface of said insulating support member and projecting outwardlytherefrom said first preselected distance, and said second metallicmembers each comprise a generally U-shaped member including a pair oflegs extending through apertures in said insulating support member andbeing rigidly crimped into position at said first surface of saidinsulating support member in electrical contact with said secondpreselected portions of said conductive paths and an integral bodymember joining said legs, said body being supported at said secondsurface of said insulating support member and projecting outwardlytherefrom said second preselected distance.
 10. A system in accordancewith claim 9 wherein said first metallic members comprise a pair ofstaples secured to said insulating support member, each of said sets ofconductive support members including said pair of staples separated by apreselected distance to define the generally planar support for saidconductive elements, and said second metallic member comprises anotherstaple secured to said insulating support member intermediate said pairof staples.
 11. A system in accordance with claim 10 wherein saidconductive elements are each of a generally circular configurationhaving opposed marginal potions supported on said pair of staples andhaving a generally central portion spaced from and maintained inselective disengagement with said another staple and adapted to bedeflected into engagement with said another staple in response to theapplication of the preselected deflecting force to said conductiveelement thereby establishing a bridging electrical contact between saidpair of staples and said another staple so as to effect an electricalconnection between said first and second preselected portions of saidconductive paths.
 12. A system in accordance with claim 6 wherein saidfirst metallic members each include a shank extending through anaperture in said insulating support member and having an annular collarat one end of a greater diameter than the aperture to preclude completepassage of said shank through the aperture, said collar abutting saidsecond surface of said insulating support member and defining a portionof the planar support for one of said conductive elements, the oppositeend of said shank being crimped against said first surface of saidinsulating support member to effect rigid emplacement of said firstmetallic member, and said second metallic member each include a shankextending through an aperture in said insulating support member andhaving a head at one end of a greater diameter than the aperture topreclude complete passage of the shank therethrough, said head abuttingsaid second surface of said insulating support member, the opposite endof said shank being cramped against said first surface of saidinsulating support member to effect rigid emplacement of said secondmetallic member.
 13. A system in accordance with claim 12 wherein saidfirst metallic members comprise collared rivets secured to saidinsulating support member, each of said sets of conductive supportmembers including a plurality of collared rivets spaced to accommodatesaid conductive elements in supporting relationship on said annularcollars, and said second metallic member comprises a headed rivetgenerally centrally located with respect to said set of collared rivets.14. A syStem in accordance with claim 13 wherein said conductiveelements are each of a generally circular configuration having amarginal boundary supported on said annular collars of said collaredrivets and having a generally central portion spaced from and maintainedin selective disengagement with said headed rivet and adapted to bedeflected into engagement therewith in response to the application ofthe preselected deflecting force to said conductive element therebyestablishing a bridging electrical contact between said set of collaredrivets and said headed rivet so as to effect an electrical connectionbetween said first and second preselected portions of said conductivepaths.
 15. A selectively energizable keyboard system comprising anelectrically insulating support board having a first surface carrying aplurality of conductive paths arranged in a preselected pattern andadapted to transmit electrical information in response to selectiveinterconnection of portions thereof, a plurality of spaced sets ofconductive staples arranged in a preselected configuration at a secondopposite surface of said support board to define a plurality ofgenerally planar support areas the ends of each of said staplesextending through apertures in said support board and terminating inelectrical contact with first preselected portions of said conductivepaths, a plurality of associated conductive staples at said secondsurface, one of said associated staples being arranged intermediate thestaples in each of said sets and electrically isolated therefrom, theends of each of said associated staples extending through apertures insaid support board and terminating in electrical contact with secondpreselected portions of said conductive paths, a plurality ofselectively actuatable, generally circular, conductive discs adapted toundergo flexing movement in response to the application of a preselecteddeflecting force thereto respectively disposed on said planar supportareas with marginal portions thereof supported by and maintained insubstantially stationary electrical contact with said sets of conductivestaples and the central portion thereof is selective disengagement withsaid associated conductive staples, the central portions of saidconductive discs being adapted to be deflected into a position ofengagement with said associated conductive staples so as to establish abridging electrical contact between a set of conductive staples and itsassociated conductive staple, thereby electrically connecting said firstand second preselected portions of said conductive paths in response tothe application of a preselected deflecting force to said conductiveelement, an overlayer of insulating material supported at said secondsurface of said support board, said overlayer including a plurality ofapertures exposing said sets of conductive staples and said associatedstaples, said apertures being adapted to accommodate said conductivediscs to restrain lateral movement thereof while permitting deflectionthereof, and means for applying the preselected deflecting force to saidconductive discs including a plurality of pushbutton members adapted tobe manually actuated to apply the preselected deflecting force to saidconductive discs to effect deflection of the central portion thereofinto a position of engagement with said associated conductive staple,each of said pushbutton members having a force applying surface inregistration with a conductive disc and an exposed surface adapted to besymbolized in a manner indicative of the electrical informationtransmitted in response to the establishment of the electricalconnection between said first and second portions of said conductivepaths.
 16. In an electronic calculator; a pushbutton keyboard systemadapted to enter electrical information in response to actuation, saidkeyboard system including an insulating support board having a firstsurface on which a plurality of conductive paths are arranged in apresElected pattern and adapted to transmit electrical information inresponse to energization thereof, a plurality of spaced sets ofconductive support members arranged in a preselected configuration at asecond opposite surface of said insulating support board to define aplurality of support areas spaced from said second surface and inelectrical communication with first preselected portions of saidconductive paths, a plurality of conductive contact members associatedwith said plurality of support members one of said contact members beingarranged within the area defined by each of said sets of contact membersand in electrical communication with second preselected portions of saidconductive paths, a plurality of selectively actuatable, generallycircular, conductive discs respectively disposed on said support areaswith marginal portions thereof supported by and maintained insubstantially stationary electrical contact with said support membersthe central portions thereof being in selective disengagement with saidassociated contact members and being adapted to be deflected into aposition of engagement with said associated contact member in responseto the application thereto of a preselected deflecting force so as toestablish a bridging electrical connection between a set of conductivesupport members and its associated conductive contact member, therebyelectrically connecting said first and said second preselected portionsof said conductive paths, means disposed adjacent said second surfacefor restraining movement of said conductive discs other than flexingmovement thereof, and means for applying the preselected deflectingforce to said conductive elements including a plurality of pushbuttonmembers adapted to be actuated to apply the preselected deflecting forceto said conductive discs to effect deflection of the central portionthereof into a position of engagement with the associated conductivecontact member, each of said pushbutton members having a force applyingsurface adjacent a conductive disc and an exposed surface adapted to besymbolized in a manner indicative of the electrical information to betransmitted by the establishment of the bridging electrical connectionbetween said first and second portions of said first and secondconductive paths.
 17. A selectively energizable keyboard systemcomprising an electrically insulating support member having a generallyplanar first surface on which a plurality of conductive paths aredisposed arranged in a preselected pattern adapted to transmitelectrical information in response to selective interconnection ofportions of said paths, a plurality of spaced apart generally U-shapedfirst conductive members arranged in a preselected configuration at asecond opposite surface of said support member, the ends of each firstmember extending through apertures in the support member and terminatingin electrical communication with first preselected portions of saidpaths, a plurality of generally U-shaped second conductive members, asecond member associated with each of said first conductive members,said second conductive members being arranged at said second surface ofsaid support member each in electrically isolated relationship with itsassociated first conductive member, the ends of each second memberextending through apertures in the support member and terminating inelectrical communication with second preselected portions of said paths,a plurality of selectively actuatable conductive elements, and meansmounting said conductive elements adjacent said second surface, arespective element being mounted contiguous to each second conductivemember and its associated first conductive member, said conductiveelements being adapted to be deflected into a position of engagementwith their respective first and second conductive contact members so asto establish an electrical connection between said first and said secondpreselected portions of said paths in response to the application of apreselected deflecting force to said conductive elements.